In 1997, approval was broadened to include children 18 months of age or older. See the following Web site for more information: http://www.fda.gov/cdrh/cochlear. Accessed July 2008. Equipment modifications led to the CLARION Bionic Ear and the Hi Resolution Bionic Ear systems, which were approved in 2002 for adults with postlingual onset of severe-to-profound (pure tone average of 70 dB or more hearing level), bilateral, sensorineural hearing impairment who obtain limited benefit, defined as test scores of 50% or less correct on a test of open-sentence recognition (HINT sentences) from appropriately fitted hearing aids and children aged 12 months to 17 years 11 months with profound, bilateral, sensorineural hearing loss who lack benefit from appropriately fitted hearing aids. See the following website for more information (use product code MCM): http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfPMA/PMA.cfm.

Accessed February 2009.

In September 2004, Boston Scientific Corp., which acquired Advanced Bionics Corp. as a subsidiary in June 2004, announced a voluntary recall of all unimplanted CLARION and Hi Resolution cochlear implant devices due to the potential presence of moisture in the internal circuitry of these devices, a condition that may cause the device to malfunction. See the following Web site for more information: http://www.fda.gov/oc/po/firmrecalls/boston09_04.html.

Accessed February 2009. This action followed an FDA inspection of Advanced Bionics' Sylmar (CA) facility completed August 25 to September 15, 2004 that identified hermetically sealed moisture in Hi Resolution 90K cochlear implant devices. On September 23, 2004, representatives from the FDA and Advanced Bionics met to discuss the findings of the FDA inspection, which revealed numerous violations of Current Good Manufacturing Practice (cGMP) requirements for medical devices. At the September meeting, Advanced Bionics agreed to correct these cGMP violations, most of which were to be addressed before the end of 2004. On February 1, 2005, the FDA issued a warning letter listing the violation, requesting documentation that violations had been addressed, demanding prompt action to correct violations, and noting that failure to promptly correct violations may result in regulatory action by the FDA. The FDA is not recommending removal or replacement of any devices already implanted in patients.

The available literature occasionally mentioned other cochlear implantation devices, including the Digisonic® device (MXM Company, Vallauris, France), the Laura device (Cochlear CTEC, Mechelen, Belgium), the 3M device (Cochlear Corp.), and the Ineraid device (Smith & Nephew Richards). However, these devices have not received approval from the FDA (Digisonic, Laura), or are no longer manufactured (3M, Ineraid).

For a list of indications for each device, refer to the FDA web site for medical devices (Product code MCM [implant, cochlear]): http://www.accessdata.fda.gov/scripts/cdrh/devicesatfda/index.cfm. Accessed February 2009.

Research Evidence Background While hearing loss may relate to abnormalities in the sound conduction system of the outer and middle ear, most severe hearing deficits in newborns and the elderly result from sensorineural abnormalities, particularly cochlear hair cell loss which limits the ability of the cochlea to convert sound vibrations into nerve impulses. This type of hearing loss is usually irreversible and has been treated with rehabilitation strategies involving hearing aids, sign language, and speech and language therapy. Amplification does not replace the function of lost cochlear hair cells and often cannot provide adequate hearing in the case of severe cochlear hair loss. If appropriate neural elements in the ear are intact and functional, it is possible to stimulate auditory nerve impulses with a cochlear implantation device to improve sound recognition.

The cochlear implant is composed of three parts, which include external components and two internal surgically implanted components. Externally, a microphone, speech processor, and transmitter coil with cables are worn. The speech processor converts sound into electrical stimuli. Internal components include an antenna and electrodes. The

Cochlear Implants - Commercial Medical Management Guideline

antenna electromagnetically captures the stimuli transmitted by the speech processor and directs this information to internal electrodes. The electrodes provide direct electrical stimulation to the auditory nerve, bypassing the transducer cells which are absent or nonfunctional. Because the cochlear implant does not magnify sound, none of its components are considered a hearing aid.

Potential candidates for cochlear implant must obtain limited benefit from hearing aids, which typically is determined by administering speech perception tests while the patient wears appropriately fitted hearing aids, often described as the best-aided condition. Cochlear implants may be considered for use in patients who acquired hearing loss after development of speech (postlingual), during development of speech (perilingual), or before development of speech (prelingual). After receiving cochlear implantation, devices are programmed on an individual basis and recipients must undergo training and rehabilitation to learn to use auditory cues obtained from the device. Advantages associated with cochlear implants include significantly improved speech reading ability, improved recognition of environmental sounds, and improved speech intelligibility.

Typically, patients undergo unilateral CI. However, bilateral CI is also performed with two devices implanted at the same time or sequentially. Theoretical advantages of bilateral implantation are improved localization of sound and improved speech recognition in noisy environments. Bilateral cochlear implantation in children is being investigated as a means to improve their access to phonologic inputs, thus providing the basis for oral language learning.

Cochlear hybrid implants (e.g., Duet EASTM Hearing System or Nucleus Hybrid cochlear implant) are currently being developed to allow auditory rehabilitation of patients who are not candidates for conventional implants because their low-frequency hearing exceeds current guidelines. Short implant electrodes are placed in the cochlea through a small cochleostomy to preserve low-frequency hearing. These devices are not approved by the U.S. Food and Drug Administration (FDA).

Francis et al., 2004; Tyler et al., 2002) However, the result of cochlear implantation are variable among individuals and may be influenced by age at cochlear implantation, duration of deafness, and presence of residual hearing.

Unilateral Cochlear Implantation in Adults with Prelingual Hearing Loss Findings from recent studies suggest that in patients with prelingual hearing loss, cochlear implantation may allow significant or at least some improvement in speech perception but that this improvement may plateau after 1 year of cochlear implant use and may be significantly less than that observed in postlingually deafened adults. (Waltzman et al., 2002; Teoh et al., 2004; Bassim et al., 2005) Another study involved the use of a nonvalidated questionnaire to assess the subjective impact of CI in prelingually deafened adults. Responses to the questionnaire suggested that CI might improve quality of life (QOL) in most of these patients by improving communication, independence, confidence, sense of safety, employment, and/or social life (Chee et al., 2004).

Santarelli et al. (2008) evaluated speech perception in 18 prelingually deafened subjects (aged 13-30 years). Word discrimination length, word and sentence identification, phoneme identification and word and sentence recognition were tested before cochlear implantation and at 6 months, 1, 2 and 3 years of cochlear implant use. Scores on all tests significantly improved after cochlear implantation, although mean values were lower compared to those achieved by postlingually deafened patients. Speech performances on both word and sentence recognition continued to increase over time also beyond 1 year after cochlear implantation. Moreover, scores on sentence recognition tests were significantly higher compared to disyllabic words at 3 years of cochlear implant use. The investigators concluded that the presence of Cochlear Implants - Commercial Medical Management Guideline an auditory input delivered by hearing aids before cochlear implantation associated with auditory-oral therapy and a good level of education may positively influence the cochlear implant outcome in prelingually deafened adults.

Kaplan et al., (2003) analyzed 198 deafened adults who underwent cochlear implantation. Of these, 44 patients were deafened pre- or perilingually. The investigator found that open-set speech recognition in prelingually and perilingually deafened adults is inferior to that achieved in postlingually deafened adults and varies according to the type of communication training they received. However, cochlear implants have significantly improved the overall communication skills and quality of life in all subgroups of patients.

Klop et al. (2007) evaluated 8 prelingually deafened patients who were implanted at a mean age of 36 (range, 21-55) years with a cochlear implant. The investigators concluded that with state of the art implants, speech perception and quality of life improve in prelingually deafened adults.

A retrospective study included 15 patients (adolescents and adults) with prelinguistic deafness who underwent cochlear implantation. The results of open-set speech perception tests, both words and sentences, were reviewed to assess auditory functioning after implantation. The results of this study indicate that individuals with long-term prelinguistic deafness can achieve significant open-set speech understanding with a cochlear implant, although there is a wide range of performance across patients. The results ranged from 0% to 74% for words and 0% to 98% for sentences. (Schramm et al, 2002) Moody et al. (2005) evaluated 8 subjects with profound congenital bilateral hearing loss who underwent cochlear implantation as adults and had at least 1 year of experience with the implant. The median for speech perception scores were as follows: visual-alone, 25.9% (range, 12.7-58.1%); auditory-alone, 5.2% (range, 0-49.4%); and audiovisual, 50.7% (range, 16.5-90.8%). Seven of eight subjects did as well or better in the audiovisual condition than in either auditory-alone or visual-alone conditions alone. The investigators concluded that this study demonstrated that some congenitally deafened adults are able to integrate auditory information provided by the cochlear implant (despite the lack of auditory speech experience before implantation) with visual speech information.

Some experts believe that adults with prelingual hearing loss are poor candidates for cochlear implantation since they show relatively little improvement in speech perception. (Copeland and Pillsbury, 2004) Additionally, the mounting evidence from electrophysiologic and neuroimaging studies suggests that long-term prelingual hearing loss leads to reorganization of the secondary auditory association areas in the brain, such that these areas have learned to interpret nonauditory sensory cues (e.g., visual cues from sign language and lip reading) as auditory information, and, without prior practice in hearing and using speech, this reorganization may limit the ability to acquire the cognitive skills needed to process complex speech signals and language (e.g., to interpret auditory cues as meaningful speech). Data from these studies suggest that there may be a finite critical period during which underlying auditory cortical plasticity may occur and after which reorganization is not reversible or not possible. (Teoh et al., 2004) In summary, well-designed studies demonstrating the efficacy of cochlear implants in prelingually deafened adults are limited. Additional studies are required to demonstrate the benefits of cochlear implants in this patient population.

American Speech-Language-Hearing Association (ASHA): According to a technical report approved by the ASHA, adults with long-term prelingual deafness usually do not develop open-set word recognition abilities. However, these patients may recognize environmental sounds and have improved lip reading ability following cochlear implantation.

(ASHA, 2004) Unilateral Cochlear Implantation in Children with Postlingual Hearing Loss Recently published studies regarding the benefits of pediatric cochlear implantation have focused on prelingually deafened children, and, therefore, data regarding the use of cochlear implants in postlingually deafened children are

Cochlear Implants - Commercial Medical Management Guideline

limited. The only study that clearly included some children (n=9) with postlingual deafness did not differentiate the results between these children and the substantially larger group of children with prelingual deafness. (Illg et al., 1999) The only evidence that could be found for postlingually deafened children was in the form of a statement made in the consensus document prepared by the National Institutes of Health, (NIH, 1995) an earlier (1994) study, and an earlier (1997) observational report. The NIH (1995) document noted that children or adults with postlingual deafness had better auditory performance after cochlear implantation than children or adults with prelingual deafness but that the difference in auditory performance between children with prelingual deafness and those with postlingual deafness lessened with time. Makhdoum et al. (1997) briefly summarized the findings from the study (Gantz et al., 1994), which evaluated 54 pediatric cochlear implant recipients, including children with prelingual deafness and children with postlingual deafness.

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